Device for measuring twists of loaded shafts



P 7, 19435 E. H. LAMBERGER ET AL 2,329,121

DEVICE FOR MEASURING TWISTS OF LOADED SHAFTS Filed Feb. 28, 1941 -3 Sheets-Sheet 1 INVENTORS fdward H. Ldmberger & fiernarg; E Lanyer ATTORNEY Sept 7, 1943. E. H. LAMBERGER ET AL 2,329,121

DEVICE FOR MEASURING TWISTS OF LOADED SHAFTS Filed Feb. 28, 1941 s Sheets-Sheet 2 Fig. 2.

WITNESSES: I INVENTORS t'award H. Lamberger &

' fir 1 Berna/ f. Longer ATTbRNEY Sept. 7, 1943. E. H. LAMBERGER ET AL 2,329,121

DEVICE FOR MEASURING TWISTS OF LOADED SHAFTS Filed Feb. 28, 1941 s Sheets-Sheet 3 emanate 24- Fly. Z 6/ wimass'gs: INVENTORS Q C? W 'award H. Lamberger 68 Z Berpg rd Lange/ ATTORNEY Patented Sept. 7, 1943 DEVICE FOR MEASURING TWISTS F LOADED SHAFTS Edward H. Lamberger, Wilkinsburg, and Bernard F. Langer, Pittsburgh, Pa., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsyl- Vania Application February 28, 1941, Serial No. 381,156

8 Claims.

Our invention relates to devices for indicatin the torque and other operating characteristics of a loaded shaft and more particularly to electromagnetic mean's'in combination with structures for measuring the torque and other operating characteristics of a shaft in relation to the angular. position of the shaft relative to a reference plane including the shaft axis. Our invention hasspecial utility with shafts having only limited access.

One object of our invention is the provision of indicating the torque or variations thereof on a shaft loaded either by a variable or constant load. I

Another object of our invention is the provision of measuring the torque variations on a shaft for each position of the shaft during one rotation of the shaft.

Another object of our invention is the provision of means for indicating and recording the torque variations on an intermittently loaded shaft as the shaft rotates.

The objects specifically stated are merely illustrative. Other objects and advantages will, no doubt, become apparent from a study of the following specification and the accompanying drawings, in which:

Figure 1 shows a horizontal sectional view of an oil well pump drive;

Fig. 2 shows a side view with some parts in IIIIII of the subject matter shown in Fig. 2; i

Fig. 4 shows an end view, viewed from line IV-IV of Fig. 2, of certain other features of our invention;

Figs. 5 and 6 are diagrammatic showings of the electrical and magnetic circuits used in our device; and

Fig. 7 is a showing of records of the torque variations on a shaft in relation to time and also the rotation, that is, angular position of the shaft.

It is usually desirable to be able to measure the torque of a rotating shaft under load, but when the load is cyclic, or nearly cyclic, widely varying, and is suspected of being subjected to highpeak values of short duration, it becomes particularly desirable and important to have our device is very useful, however, our'device' is not limited to oil well pumping equipment. Our device is of special utility with shafts accessible at one end only as shafts of gear transmission systems, and others. Of course, our device is not limited to shafts accessible at one end only but may also be used'with any shaft where at least one end is available. For instance locomotive axles and many shafts in transmission gear systems are available at both ends, whereas a ship propeller shaft has only the end at the gear box available. K

In addition to measuring torque values, it is often important to know at what angular position of the shaft the peak values or variations in torque occur; measuring constantand varying torques and also meansfor determining the torque variations in relation to the angular position of the shaft in relation to a reference plane including theshaft ax1s.

, In Fig. 1 we show a transmission gear for an oil well pumping equipment. The engine, or motor (not shown), through suitable meansdrives pinion l, which inturn drives the spur gear 2 rigidly attached to the shaft 3. at region 4.

The shaft 3 is hollow bored.(not necessarily but preferably to the full length as shown) to some relatively small diameter. This relatively small hole along the center of the shaft reduces the strength of the. shaft in torsion as well as bending. This reduction in strength is negligible, however. In fact large shafts are very often hollow board to reduce the shaft weight, and also to permit inspection of the shaft. 1

Into this central hole, we fit a reference shaft 5. This reference shaft has a portion 6 which is of such a diameter as to afford a secure press fit within the main shaft 3 at region 1. Except for this press fit section, this reference shaft is of sufliciently smaller diameter to assure adequate clearance between it and the main shaft.

The reference shaft 5 is selected to have sufficient rigidity so that it doesnot come in con tact, other than at region l, with the main shaft under operating conditions. In case of long shafts, locomotive axles or ship propeller shafts, the reference shaft may be supported by antifriction bearings. It is not necessary that the reference shaft be solid as shown but'a pipe constructionmay be used. The free end of the reference .shaft may also be supported at its free end so that relative rotation betweenthe reference' shaft and the main shaft is notaffected;

In Fig. 1, the driven member is a crank arm 8 for operating the walking beam, mounted on the Samson post, and thus the sucker rod of the oil well pumping equipment; The crank arm 8 is rigidly securedto the shaft at 9 whereas the driving gear 2 is secured at l. This meansthat as Our device includes means for The free end It of the main shaft 3 will be in V the same angular position as region 4. The free end I l of the reference shaft 5, on the other hand will be in the same angular position as region I. It is thus clear that for any giver-i location of region 1 between regions 4 and 9, there will always be a relative angular displacement between the shaft ends I!) and H, while stationary or while rotating, proportional to the torsional load on the shaft. 7 Should thepi'e'ss fit or region I be centered at region 9 or located to the left of '9, then theangular displacement between In and H would be equal 't'o'the total angular displacement (shaft twist) along the shaft. 'B'y locating the region '4 closer to the end '10 any desired siffalleiportion of the total sh-aft twist may be made available between the 'aft en'tls I and I1 To measure the relative angular displacement eetweefi 'shaft ends I a and l! we provide a special arrangement of two magnetic 'stiain'gages. g The two magneticstrain gages are so mounted on the shaft ends H3 and ll "ast'o' accurately measure the relative motion between them. The meunung may e better unders'tood from a re rer'enc'e to Figs. 2, 3, and 74. 1'amiiiated'doifes l2, l3, M and 15, of generally E shape are, by sifite able means, such as b'o'lts, secured to the shaft end it and spaced from sueh shaft e'nd 'by the non-magnetic blocks H and 11. The 'c'ente'riteg's of the E shaped cores are provided with n3ag= netiz ing coils 21,22, 23, and 21s as shown in Figs. am l Bolted to the and H of -tlie re fiencc shaft 5 is the non-magnetic crossbar {IQ-carrying}; pair f ai h'a d a re a 2.9 ,fl i' he? shone-d in the sin-s of rotation transits: When reiative angmar motion take-s placetetw, fyeiias it and 11, the air gaps between 1-2 a d I59 and between and increase and the air gaps tween I 3an'd f9 and F4 and 2213 decrease or vice versa, dpendingoh whether-the shaft end 'll moves counterclockwise with reTrehee-te shaft end Ill or moves clockwise with reference te sl'i'aft end 10.

's char'rges the reluetahce of' 'the in paths in the 'four iron caress d changes the "fiedances of tneezils 2 1 ,12, 23 and '21 wouii" them. By" "ease-er four gages mounted as Win, We ob'taih atftorfiatl dampen tiofi Show, would inords'bllt the ttvb l'ower all gaps wbuld correspondingly decrease.

It is apparent-therefore, by proper grouping of the" cons; automatic compensation is obtained. By associating coil 21 witheoil 2'4 'ohe legof a Wheatstorre bridge circuit and-by associating cons 2 2' and 23 in the other leg of a- Wheatston'e bridge circuit; there is thus in each p'airxof associated 'coils one with increased air gap and one with decreased air gap. Thus, if the reference shaft should sag, ineach pair of associated coils there is one cell with increased impedance and one cell with decreased impedance so thatthe two circuits remain'balanced insofar as shaft sag is concerned. The associated eons may be connected in seriesas showers Fig. 5, or in parallel as shown in Fig. 6.

meek it is bolted to end u.

However, to eliminate as much as possible any movements of the end H of shaft 5 with reference to the end N1 of shaft 3 other than angular motion, We mount the end II on the end [0 of shaft 3. A block 25 is bolted to end H3 and a These two blocks are secured to each other by means of leaf springs 21 and 28. These springs are sufliciently rigid to form either compression structure or tension structure to thus hold the shaft 5 centralized, regardless of the angular positions these springs may hold with reference to a plan of reference including the axis of shaft 3. The springs are, however, sufliciently resilient transverse their longitudinal directions so as to permit free relactive angular motion of the ends I0 and H. That is, "o radial mo'tmnor shaftli can take 'p1ace, since the extension of springs 21 and 2B intersect at the common axis of shafts 3 and 5, yet angular motionis free.

Toproperly energize the coils 21, 22, 23, and 2'4, the shaft end I!) is provided with the brush and slip ring structure shown in Figs. 2 and 3. The connection is not shown in these figures because that will become clear from a study of the tir cfu'it's shown iri Figs. Band 6. The slip rings are designated by the referee-be characters 2a, 3a and SI.

In Figs, 5 and da source of alternating'cufl rent is indicated by buses fi and hi1 adjustable cent 'er -t'ap potentiometer impe ance is shown at P having the portions 34 and 35. The circuits are thus simple wheatstoh'e'hridge"cir cults; In Fig. '5', coils 2"! and 2 4, connected in series, constitute oneleg, c'oils 22 and 23, con= necte'd in series, constitute another leg, and the portions 34 and 35 of the fiot'eriti letter can stitu te the other legs whereas in 6 coils 2| and 2! are connected in parallel a'r'i'l coils and 2-3 are connected in parallel. Qthe'r'w'i'se Figs. 5 and 6 are the same.

The recording meter M records are variations of torque. The recording meter may be of any well known type that will were the 'clr'ciii't shown. The carve this 'm'e'ter reesres may take any shape'deiier'iding' on the type -of*load driven For a given oil'- wllpumping eciu eht tested, the curve was similar 'te that sh i'vn ty ripper curve ihFig; 7'. The meter may also be of the indicating To correlate the tor ue curve with the shaft movement, we provide Still further equipment mounted at the ends [0 and I I. A crossbar E8 is bolted to the ens H! or shaft "3', and to this cross on is hol ted a stud 4T for supporting Contact carrying disc 42 having the contact pointer 52.

sum 41 eateriesthrough an annular discuss mem er '43- can eg, in a peripheral groove, a high stance; res stor 4 5 or very near zero tearjierature eoemint. The resistor, consisting preferably of a single s'ol id wire, extends, except gar a anal-1 gap, over substant-isiiy e66 of the disc A battery B is interconnected with the resistor as as and a recording voltmeter it, in structure cementing part of recording ie, isconnected to eneju ction of the battery thence tc'a binding post 4 1, a brush "4%,. a slip ring 49 to the Contact point at and then back to the battery through a, portien of resistor 45. The amount or included in the circuit oi the recording 'meter depends "on the angular position of pointer 52. The voltage thus recorded by the meter will vary in icated ey the rower ciirve '62 shown in Fig. 7. This curve '62, since the disc shaft to the rightof the said rigid connection is 43 is stationary and pointer 52 moves with shaft 3, thus indicates the position of crank arm 8 and as correlated in Fig.7 shows the torque variations in relation to shaft position and in relation to time. Note the timing wave 10. In practice the two records are made on the same recording sheet driven at a constant speed. That is meter 46, meter M, and a clock mechanism for driving a recording sheet at a constant speed are'combined in one structure. Such recording meters are well known in the art and need not be described in detail. The timing wave 10 may be produced in any well known manner. Since the recording mechanism may be operated by a timing device as a clock, it is evident that the timing wave 10 may constitute the graduations at the edge of the recording sheet. If, as is sometimes the case for recording meters, the recording sheet is not operated strictly in accordance with time, then a timing fork may be used to actuate a pointer for marking the timing wave, as"), on the recording sheet. The pointer 52 may be set for any desired angular position of the shaft'3 so that the pointer 52 passes over the gap at 60 at a desired crank position. The two curves BI and 62 arethen in the most logical relation as shown in Fig. 7.

Assuming a recording type of instrument "46 including a constant speed chart, then any devia tion of the shaft motion line (the lower curve 62 in Fig. 7) from a straight line will also indicate a variation in speed of main shaft 3. Shouldreversal of direction of rotation occur,this will be indicated by reversal of the slope of the shaft motion line. This variation in speed is shown at 1 the right at'curve 62'. p I

From the foregoing disclosure, it will be apparent that we provide apparatus bymeans of which the shaft torque is measured by means originating within the shaft itself and which means are rugged and reliable.

With our device, especially where but one end of the shaft is available, there is no interference with normal service, there is no interference with the normal use and arrangement of the shaftin the mechanical system, and no extra intermediate elements are required in the mechanical system. Our arrangement further makes it possible to directly apply magnetic strain gages with the result that accurate measurements of high frequency torque variations may be made. Further, our'particular arrangement of magnetic strain gages for measuring torque is applicable in cases Where the cylindrical surface of the shaft is not 3' available for mounting instruments thereon, but one end of the shaft is available. Further, the combination of the slide Wire device and the torque device provides means for determining the angular position of the shaft for any torque value or variation therein and for showing any variation of shaft speed or reversal of rotation.

The foregoing disclosure and the showings made with the description are merelyillustrative of the principles of our invention and are not to be interpreted in a limiting sense. The only limitations are to be determined from'theappended claims in which we claim as our invention:

disposedinspaced relation to the outer shaft and terminates in the region of the right-hand end of the outer shaft; means for applying a fo'rcecouple of a given rotational sense to the outer shaft at a region to the right of said rigid connection; means for applying a force couple of an opposite rotational sense to the outer shaft at a region to the left of the region of the application to the outer shaft of thefirst mentioned force couple, whereby any twist inthe outer shaft between the regions of the applications of the two force couples will produce a relative rotation of the right-hand ends of the concentric shafts; a first electromagnetic member, having an energizing coil, mounted on the right-hand end of the outer shaft; a second electromagnetic member, having an energizing coil, disposed in spaced facing relation to the first electromagnetic member also mounted on the outer shaft; a third electromagnetic member,-having an energizing coil, mounted'on the outer shaft; afourth electromagnetic member, having an energizing coil, disposed in spaced facing relation to the third electromagnetic member'also mounted on the outer shaft; a pair of magnetic members, one disposed in the space between the first-and second electromagnetic members and the other disposed in the space between the third and fourth magnetic members, mounted on the inner shaft; whereby any relativerotation of the right-hand ends of the concentric shafts will alter the disposition of said pair of magnetic members with reference to the electromagnetic members to thus alter the impedance of theyenergizing coils; a Wheatstone bridge circuit having input and output terminals including in one leg an impedance normally,

when there is no relative rotation of the righthand ends of the concentric shafts, matched to the impedance of the coil of the first electromagneticmember'and the coil of the fourth electromagnetic member,'both connected in a second leg of the Wheatstone bridge, and including in a third leg a second impedance normally, when there is no relative rotation of the right-hand ends" of the concentric shafts, matched to the impedance of the coil of the second electromagnetic member andthe coil .of the third electromagnetic member, both' connected inthe fourth leg of the Wheatstone bridge; a source of alternating current connected to the input terminals of the Wheatstone bridge to energize the-said coils; and arecording meter connected to the output terminals of the Wheatstone bridge for recording the variations in relative rotation of the'right-hand ends of the concentric shafts'by reason of the action of said force couplings, to thus measure the twist in that predetermined length of the outer shaft between the region of connection of said inner shaft to said outer shaft and the'region of connection of said first mentioned fore couple to said outer shaft.-

In a system for measuring the'twist'in a predeterminedlength of a shaft, in combination, a shaftconcentric within said shaft, the inner shaft being rigidly so connected to theouter shaft ataregion to the left of the right-hand ends of the concentric shafts that the portion of the inner shaft to the right of the said rigid connection isdisposed in spaced relation to the outer shaft and terminates in the region of the righthand end of the outer shaft; means for applying a force couple of a given rotational sense to the outer'shaft at a-region; to the right of said rigid connection; ,nicans'for-applying a dome couple-cf ano'ppoizite rotational sense to :the outer shaft as a region to the left of the regionof the application-to-the outershaftof the firsvmentioned force couple, wherebyv any twist the outer shaft between the regions of the applications of the two force couples'will produce a relativero tation of the right-hand ends of the concentric shafts; a first electromagnetic member, having an energizing coil, mounted on the right-hand end of one of the, concentric shafts; a second electromagnetic member, having an energizing coil, disposed in aspaeed facing relation to the first electromagnetic member mounted :on the same shaft as the first electromagnetiomember; a third electromagnetic member, having an energizing coil, mounted on the same shaft asthc first electromagnetic member; a fourth electromagnetic member-,ahavingan energizing coil, dis"- posed in spaced racing relation to the third electiomagnetic member also mounted on the same shaft as the first electromagnetic member; a pair of magnetic members, one disposed in the space betwen the first andseco d electromagnetic members and the other disposed in the space between the third and fourthmagnetic members, mounted on theright hand end of the other one of said concentric shafts; wherebyany relative rotation or the right-hand erds of the concentric shafts will alter thedisppsition of said pair of magnetic "members reference to the electromagnetic members to thus alter the ims penance of the energizing coils; a Wheatstone bri ge circuit having input and output terminals including iii one leg an impedance normally, when there is no relative rotation of 'thefrighthand ends of the concentric shafts, matched to the impedance or the coil 'of the iii'st electromagnetic member and the con crnie fourth electroinagn'etic member, bofth connected in a second leg of the Whe'atstone bridge, and including in a third leg a second impedance nonnafly, whet; there is no relative rotation of the right-hand ends of the concentric shafts, matched to the impedance of thec'oi'l or the second electr6iiiag eerie member and the chil brine third electroma net c member, both connected in the fourth leg of the Wneatstone bridge; 'a-sou'rc'e of alterna curr nt conn cted to the input terminals of the Wh'e'atstonebfidgc to energize the said earls, and a merger connectedto the 'outputterininals of the Wheatstbne bridge for measuring the variations iii relative rotation "of the righthand ends of the concentric shafts by reason of action of said-force Couplings, 1:9 thus me sure the twist in that prcdetennined length-ct the i aft between the region or connection in "of shart to said outer shaft and re: rim or connecticn of sa-id first mentioned force couple to said outer shaft." Q g H I r g 3; In a system for measur mg the twist in a reaeteniimec 1eiig t-l'ib f'a shaft, in inpinaticn, a shaft concentric Withiii said shaft; the ini'rer shaft being rigidly so connected to the outer shaft at a region t6 "the left of the right-hand endsof the concentric shafts that the cornea of the inner shaft to ther iglit of the said rigid (xiii-- motion is disposed in. spaced rel'ati'oirto' the outer shaft and terminates in the region of the right hand End ofthe Outer 'sh aftj a can '(if leer springs disposedat an angle to each other and radially disposed of the common axes of the two shafts, the outer endso-f the springs being rigidly secured to the outer shaft and the inner ends being rigidly secured to the inner shaft; whereby free relative rotation -of the -right=harid ends of *the shafts is permitted but the inner shaft is prevented, by reason-of its tendency to sag, from moving out of the axial alignment of the axis of the outer shaft; means for "applying 'a force couple of a given rotational sense to the outer shaft at a region to 'therightof said rigid connection; mean-s fora'pplyinga force couple of an opposite rotational sense to the outer shaft 'at a region to the leftscf the region of theapplication to the outer shaft of the first mentioned force couple, whereby any twist in the outer shaft between-the regionsof the appl-ications'of the two force couples will produce a relative rotation of theright h-and ends of the concentric shafts; a first electromagnetic memb er; having an energizing coil, mounted on the right=hand end of the outer shaft; a second electromagnetic member, having an energizing coil; disposed in spaced facing relation to the first electromagnetic iner-nber also mounted on the outer shaft; a third electromagnetic member, having an energizing coil, mounted on the outer shaft; a fourth electro magnetic member having an energizing coil, disposed in spaced facing relation to the third electromagnetic member also mounted on the outer shaft; a pair of magnetic members, one disposed in the space between the first and second electromagnetic members and the other dis- .posedin the space between the third and fourth magnetic members, mounted on the inner shaft; whereby any relative rotation of the right han-d ends of the concentric shafts will alter the disposition of said pair ofmagnetic members with reference .to the electromagnetic members to thus alter the impedance of the energizing coils; a Wheatstone bridge circuit having input and output terminals including in one leg an impecaneehormauy, when there is no relative rot'at'io'n 'of the right-hand ends of the concentric shafts, matched to the impedance of the coil of the first electromagneticinem ber and the coil of the fourth electromagnetic member, both conhctd in a second leg o'f the Wheats'tone bridge, and ihcludirigfin a third leg a second impedance h'oiifially, weathers is no relative rotation of the right-hand ends or the concentric shafts, matched to the iiiipd'a'rice of the coil of thesesond electromagnetic member and the coil of the third e ectromagnetic matter, both connected n the fourth leg or the Wheatstone bridge; a source 6f alteriiatiiig current connected to the input terminals or the Wheatstone bridge to en- 'ergize the said coils; and a recording met-er connected to the output terminals of the VVheatston'e bridge for fecordihgthe variations iii relative rotansn or the right-hand efids of the concentric shafts by reason (if the action of said force coupli'ngs, to thus i'nas'ure the twist in that predetermined length of the outer shaft between the region "or conn ction of said outer shaft to said inner shaft the 'r'gionof connection of said first mentioned force couple to said outer shaft.

4. In a systemior measuring the twist in a predetermined length f a shaft, in combination; a shaft concentri Within "said s aft, the inner shaft being rigidly so connected to the outer shaft at a region t th e left of the right-hand ends of the concentric shafts that the portion of the inner shaft to the right of the said rigid connection is disposed in spaced relation to the outer shaft and terminates in the region of the rightshafts,the outer ends of the springs being rigide ly secured to the outer shaft and the inner tends being rigidly secured to the inner shaft, wherebyf free relative rotation of the right-handends of a the shafts is permitted but the inner shaft ispre-" vented, by reason of its tendency to sag, from moving out of the axial alignment of the axisrof: the outer shaft; means for applying a force couple of a given rotational senseto theeuter shaft at a region to the right of said "rigid con nection; means for applying a force couple, of. -an, opposite rotational sense to the outershaft at a region to the left of the regionof the application to the outer shaft of the first mentioned force couple, whereby any twist in theouter-shaft between the regions of the applications of the twoforce couples will produce a relative rotation. of the right-hand ends of the concentricshaftmta" first electromagnetic member, having an energize ing coil, mounted on the right-hand end of one of the concentric shafts; a second electromag netic member, having an energizing coil, dispo'sed in aspaced facing relation to the first electromag':

netic member mounted on the same shaft as'the first electromagnetic member; a v third electrothe leftof the right-handends of the concentric shafts thatthe portion of the inner shaft to the right "of the said rigid connection is disposed in spaced relation to the outer shaft and terminates in the region of the right-hand end of the outer shaft; means for applying a force, couple .of av given rotational sense to the outer shaft at a region to the right of said rigid connection and of a-magnitude suflicient to rotate the outer and inner shafts; means for applying a force couple ofan opposite rotational sense to the outer shaft at a'region to the left of the region of the applica- 17101117017116 outer shaft of the first mentioned force couple, whereby any twist in the outer shaft, be-

" f tween the regions of the applications of thetwoforce couples will produce a relative rotation of the right-hand ends of the concentric shafts; a

first electromagnetic-member, having anenergizmagnetic member, having an energizing; coil,

mounted on the same shaft as the first Ielectroi magnetic member, a fourth electromagnetic member, having an energizing coil, disposedin spaced facing relation to the thirdelectromag i netic member also mounted on the same shaft as the first electromagnetic member; a pair :of.

magnetic. members, one disposed inlthe space between the first and second electromagnetic mm-p bers and the other disposed in the spacebetween;

the third and fourth magnetic -members', mounted on the right-hand end off the otherone of said concentric shafts; whereby any relative rotation of the right-hand ends of the concentric shafts will alter the disposition of said pair of magnetic members with reference .to'ithe electromagnetic members to thus alter: the, impedance of the energizing coils; a Wheatstone; bridge circuit having input and outputaterminals including in one leg an impedance normally ywhen there is no relative rotation of the right; hand'ends of the concentric shafts, m'atched;to' the impedance of the coil of the first electromagnetic member and the coilof the fourth-electromagnetic member, both connected in a'se'cond leg of the Wheatstone bridge, andincluding in a': third leg a second impedance normally, when there is no relative rotation-oftthgrighthand ends of the concentric shafts, matched toithe irne pedance of the coil of the secondlelectromagnetic? member and the coil of the third ele'ctromage.

netic member, both connected in thezfourth leg of the Wheatstone bridge; a source of alternating currentconnected to,the input terminals-of the Wheatstonebridge to energize. the said coils, and; a meter connected to the output terminals ofthe Wheatstone bridge for measuring the variations, in relative rotation of the right-handends; of the concentric shafts by reasonof the. action of said force couplings, to thus measure the twist in' that predetermined length of the outer shaft between the region of connection,v of said outer shaft to said inner shaft and the region of connection" of-said first mentioned force couple to said outer shaft.

5. In a system for measuring predetermined length of a main rotating snarnm combination, a shaft concentric within said shaft, the 'inner, or reference shaft, being rigidly. so con-,1 nected. to the outer, or main, shaft at a'regi'ontoltnetwist m a].

. chart, said first recording device of said meter being connected to the output terminals of the,

ing coil, mounted on the right hand end of the outer shaft; asecond electromagnetic member,

having anenergizing coil, disposed in spaced facingrelation to-the first electromagnetic member also mountedon the, outer shaft; a third electromagnetic member, having an energizing coil,

mounted on the outer shaft; a fourth electromagnetic membenhaving an energizing coil, d isposed in spaced facing relation to the third electromag-- netic member also mounted on the outer shaft; a pair of magnetic memberson disposed in the space between the firstand second electromagnetic members andthev other disposedin the p c between the third andfourthmagnetic members, mounted on'the inner shaft; wherebyany relative rotation of the right-hand ends of'the concentric shafts will'alter the; disposition of said.

no relative rotation; of the right-hand ends of the concentric shafts, matched to the impedance .of. the. coil of the second electromagnetic, member and the coil of the third; electromagnetic member, both connectedin the fourth leg of the Wheatstone bridge; asource of alternati ng cure rent connected to the input terminals ,o-f the Wheatstone bridge to energize the said coils; and a recording meter'comprising a first and a second recording device and a constant speed recording Wheatstone bridge forrgraphically recording on said constantspeed chart the variations, in-relative rotation of ,the right-handends-of the concentric shafts by reason of the action of said force couplings, to thusmeasure the twist in that predetermined length of the outer shaft between the region of connectionof the outer shaft to the innerv shaft and'the region of connection of the first mentioned force couple tothe outershaft,

means forproducing a pulsating voltage corresponding to, the angular motion of said outer shaft and having a frequency whichisthe equal of the revolutions per minute of said outer shaft, circuit means interconnecting said means for producing a pulsatingjvo ltage with said second recording device of said meter whereby theshaft angularmotion. i graphically. recorded on said constant speed chart adjacent saict graphic; rel; cording of the variations inrelative rotation of: the right-hand ends of the concentric. shafts, the combination of saidgraphic recordings'providing an indication ofthe angularv shaft positionfon any given-torque. 1

6: In a system for measuring the twist in apnedetermined length of a main rotating. shaf;t ,..in.: combination, a shaft concentric withinsaid-shaft, the inner, or reference shaft, beingrig-idlyso cone. nected to the outer, onmain, shaft at a region-to. the left of-the right-hand ends ofthe. concentric. shafts thatthe portion of the innenshaft to the right of the said rigid connection isdisposed in. spacedrelation to the outer shaft and terminates, in the region of'the right-handend osthe; outer shaft; a p'airof leafsprings disposed at an angle, to each other and'radially disposed offthecome.

mon axes of the two shafts the outer ends of the H springs being rigidly secured. to the outer shaft and the inner ends being rigidly. secured to the. inner shafhwhereby-fre'e relative rotation ofthe. right-handends of- -the.sh-afts is-permittedbut the. inner shaft; is prevented, byreaso-n ofi-its'tendency, to sag f-rorn moving outotthe axial alignment of: the axis of the outer shaft;- meansfor-applying a.

force couple of a given rotationai sense. to the. outer shaft at a region to the right-of-=-saidv rigid,

connection and of a magnitude-sufficient to ro tate the outer andinn er shafts ymeans forv apply-.. ing a force couple of -an- QPPosi-terotationalsonsc. to the outer shaft at a region of theleft of the region of the apblication of theouter shaftof the. first mentioned force couple, whereby anytwistin. the outer shaft, between theregions-of;- the appli.. cations of the two force couples will. producea. relative rotation or the right-hand" ends. of the. concentric shafts; a firstelectromagnetio. meme. ber; having an energizing coil; mounted; on. the. right-hand en'q of the outer-shaftsasecond elec'e. tromagneti-c m mber, having an energizing coil; disposed inspaced; facing relation to theifirst. electromagnetic memberalso mounted on the. ojter shafti a, third; electromagnetic member,-

having an? energizing coil, mounted on the. outer shaftg' a f gurthfelectromagnetio member, havingtion to the. third electromagneticrmembenalso.

an energizingcoil; disposed in spacedfacinglrelaa disposed the space between the.

memb r rst nd second'electromagnetio members: andl' the other disposed-in the space between thethircl: and fourth, magnetic members, mounted-l on the inner shaft; whereby'any relative rotation of-- the. right hand; ends of the co'ncentric shaftswillaalter,- the disposition of said; pair of magnetic members with referenceto theclctrornagnetiomembers- 120.. thus not; the impedance of the energizingwils? a Wheatstonebridge circuit having input and output terminals iQQlPS ng in o -gag an imped ance normally, when there 'is no relatite rotationi ends of-"the concentric shafts,

f. h ri t-hand matched to the impedance electromagnetic member and the coil" onthe. fourth electrorn gnetic member; both connected in a. second leg of the Wheatstone bridge, and including in a third leg a second impedanceunore. mally, when there is no relative rotation. right-hand ends of the concentric shafts, matched to the impedance ofthe coil of the sect 0nd el ectrornagneticrnember and the coil'of-the third. electromagnet mernber, both connected ine fourth 1a. o t l zhee st e e i som of alternating current connected to th' input ter I of the,

I means forproducing. a. pulsating voltage comers sponding to the angular motionofrsairt outer shaft andhaving. a. frequency which. is. the. equal of; the revolutionspen minute or said. outer shaft, circuit; means interconnecting said. means, for; producin a pulsating voltage with said second. recording device. of said; meter wherebyv the. shaft:v angular.- motion. is graphically recorded on. said; constant. speed. chart adjacent said: graphic recording. of the. variations in. relative rotation; ofr the righthand. ends of. the concentric shafts, thecombina: tion. of said. graphic recordingspr-oviding animii; cation of theangular shaft position. for any-given;

torque.

'7. In. a. system. for measuring t e twist in apt-.9: determined; length of: a main. rotating. shaft. n; combination, a shaft concentric with-insaidshafit the inner, or reference shaft, beingrigidly so.con.-.. nested tothe outer, or: main, shaft. eta; resiorrto. the. left. of. the;right-hand ends. of:- the-concentric. shafts. that. the portion of, the. innen shaftto the; right of, the said. rigid connection; is disposed. in: space relation. tolthe outer-shaft andtemnmates in the region or; theright-hand: end: of: the. enter. shaft; means for applying a. force couple. of: a, given rotational; sense to. the outer she-It. at. a. region tolthe right of,- said. rig-id connection.- andaof: a magnitude sumo-lent to rotatethe: Qutenand: inner shafts; means. for applying a force couple of; an. oppositelrotational' sense tothe cuter shaft;

. at alregion totheleftof the resioncf the applica;

tionto the outer. shaft; of; thefi st ment oned; force .couple, whereby. any twist; in. the outer-shaft, between the.regionsjof-the. applications cfrthe two. force. couples. will: produce a. relative rc tation; of th ..right=hand. endsof. the concentric she-fist a. r t eiectromaenc iomembcr, havina an. on gizing coil; mounted; on the rightehand; end: of: one. of" the. concentric shafts a second eleotrm. magneticmember, having. an. energizil-ig-v coil; dis=-.

I posed. in spaced: facing relation. to the first:.elcc.-.. tromagnetiomember. mounted on. the same shaft asthe-lfirst electromagnetic member; a. third eleca, tnomag-netic member, having an energizing. coil, mounted-onthesameshaftas the first electro.-.

-. magnetic member; a. fourth electromagnetic member, having an, energizing. coil,- disposed: in. spaced facing-relation to. the third 'electromagr. netic memberalso mounted onthesame shaftas; the -first electromagnetic .memben; aipair off-armie-- netic members, one disposedin thespaoebetween. the first and second-electromagnetic.membersand the other disposed in the spacebetweenththird; and-fourth magnetic members, mounted: on the; right-hand endof'the. other. one crsaidmn enir a shafts, whereby any relative rotation of the right; hand endsof the concentric.shaftswill alter the dispositioniofi said pair. of m netic msmhe s rererencemrne.electroma n ticmemheratetlai alterthe impedance of: the; encseis as'e ihs; a.

-. Wheatstone brideacir uitrhe iufiihhlih ace.- 0111a put terminals including in one leg an impedance normally, when thereis no relative rotation of the right-hand ends of the concentric shafts, matched to the impedance of the coil of the first electromagnetic member and the coil of the fourth electromagnetic member, both connected in a second leg of the Wheatstone bridge, and including in a third leg a second impedance normally, when there is no relative rotation of the right-hand ends of the concentric shafts, matched to the impedance of the coil of the second electromagnetic member and the coil of the third electromagnetic member, both connected in the fourth leg of the Wheatstone bridge; a source Of alternating current connected to the input terminals of the Wheatstone bridge to energize the said coils; and a recording meter comprising a first and a second recording device and a constant speed recording chart, said first mentioned recording device of said meter being connected to the output terminals of the Wheatstone bridge for graphically recording on said constant speed chart the variations in relative rotation of the right-hand ends of the concentric shafts by reason of the action of said force couplings, to thus measure the twist in that predetermined length of the outer shaft between the region of connection of the outer shaft to the inner shaft and the region of connection of the first mentioned force couple to the outer shaft, means for producing a pulsating voltage corresponding to the angular motion of said outer shaft and having a frequency which is the equal of the revolutions per minute of said outer shaft, circuit means interconnecting said means for producing a pulsating voltage with said second recording device of said meter whereby the shaft angular motion is graphically recorded on said constant speed chart adjacent said graphic recording of the variations in relative rotation of the right-hand ends of the concentric shafts, the combination of said graphic recordings providing an indication of the angular shaft position for any given torque.

8. In a system for measuring the twist in a predetermined length of a main rotating shaft, in combination, a shaft concentric within said shaft, the inner or reference shaft, being rigidly so connected to the outer, or main, shaft at a region to the left of the right-hand ends of the concentric shafts that the portion of the inner shaft to the right of the said rigid connection is disposed in spaced relation to the outer shaft and terminates in the region of the right-hand end of the outershaft; a pair of leaf springs disposed at an angle to each other and radially disposed of the common axes of the two shafts the outer ends of the springs being rigidly secured to the outer shaft and the inner ends being rigidly secured to the inner shaft, whereby free relative rotation of the right-hand ends of the shafts is permitted but the inner shaft is prevented, by reason of its tendency to sag, from moving out of the axial alignment of the axis of the outer shaft; means for applying a forc couple of a given rotational sense to the outer shaft at a region to the right of said rigid connection and of a-magnitude sufficient to rotate the outer and inner shafts; means for applying a force couple of an opposite rotational sense to the outer shaft at a region to the left of the region of the application to the outer shaft of the first mentioned force couple, whereby any twist in the outer-shaft, be-

tween the regions of the applications of the two force couples will produce a relative rotation of the right-hand ends of the concentric shafts; a first electromagnetic member, having an energizing coil, mounted on the right-hand end of one of the concentric shafts; a second electromagnetic member, having an energizing coil, disposed in spaced facing relation to the first electromagnetic member mounted on the same shaft as the first electromagnetic member; a third electromagnetic member, having an energizing coil, mounted on the same shaft as the first electromagnetic member; a fourth electromagnetic member, having an energizing coil, disposed in spaced facing relation to the third electromagnetic member also mounted on the same shaft as the first electromagnetic member; a pair of magnetic members, one disposed in the spac between the first and second electromagnetic members and the other disposed in the space between the third and fourth magnetic members, mounted on the righthand end of the other one of said concentric shafts, whereby any relative rotation of the righthand ends of the concentric shafts will alter the disposition of said pair of magnetic members with reference to the electromagnetic members to thus alter the impedance of the energizing coils; a Wheatstone bridge circuit having input and output terminals including in one leg an impedance normally, when ther is no relative rotation of the right-hand ends of the concentric shafts, matched to the impedance of the coil of the first electromagnetic member and the coil of the fourth electromagnetic member, both connected in a second leg of the Wheatstone bridge, and including in a third leg a second impedance normally, when there is no relative rotation of the right-hand ends of the concentric shafts, matched to the impedance of the coil of the second electromagnetic member and the coil of the third electromagnetic member, both connected in the fourth leg of the Wheatstone bridge; a source of alternating current connected to the input terminals of th Wheatstone bridge to energize the said coils; and. a recording meter comprising a first and a second recording device and a constant speed recording chart, said first mentioned recording device being connected to the output terminals of the Wheatstone bridge for measuring the variations in relative rotation of the righthand ends of the concentric shafts by reason of the action of said force couplings, to thus measure the twist in that predetermined length of the outer shaft between the region of connection of the outer shaft to the inner shaft and the region of connection of the first mentioned force couple to the outer shaft, means for producing a pulsating voltage corresponding to the angular motion of said outer shaft and having a frequency which is the equal of the revolutions per minute of said outer shaft, circuit means interconnecting said means for producing a pulsating voltage with said second recording device of said meter whereby the shaft angular motion is graphically recorded on said constant, speed chart adjacent said graphic recording of the variations in relative rotation of the right-hand ends of the concentric shafts, the combination of said graphic recordings providing an indication of the angular shaft position for any given torque.

EDWARD I-I. LAMBERGER, BERNARD F. LANGER. 

